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Cable not tight enough? Shifter/rear derailer adjustment?

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Cable not tight enough? Shifter/rear derailer adjustment?

Old 03-13-09, 11:07 AM
  #1  
j. hughes
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Cable not tight enough? Shifter/rear derailer adjustment?

Bike has older 600 level STIs that generally work very well. When shifting down to the lowest gear (biggest cog) the derailer (also 600) will move just fine but won't stay there and shifts back up to the second lowest gear. I could hold the lever in and it would stay in the correct gear but when released it shifts back down. The DT adjustment is all the way out as is the adjustment at the derailer. I was going to change my cables out soon anyways, but is this just a tension issue?

Thanks in advance.
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Old 03-13-09, 11:32 AM
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onbike 1939
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It is more likely that the "L" limit screw needs to be unscrewed a little, allowing the chain to settle on the large sprocket. It may be worth pulling the cable down with your hand while rotating the pedals to check the range of movement of the RD and making sure the RD is lubed properly also.
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Old 03-13-09, 01:10 PM
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Originally Posted by onbike 1939 View Post
It is more likely that the "L" limit screw needs to be unscrewed a little,

If a derailleur can be easily shifted into the last sprockt the limit screws generally do not need adjustment.

This sounds like either a cable tension problem (too little cable tension), the shifter is somehow damaged so it does not hold the derailleur in the last gear (this is unlikely), or maybe the cable has slipped so much that you are using all the clicks in the shifter to get to the second-last cog and have no more clicks left to hold it on the last one (this is essentially a cable adjustment problem, too).

Try screwing in all the barrel adjusters; loosen the cable pinch bolt, pull the cable tight and retighten the bolt; reset adjust barrel adjusters until shifting is perfect.

A better description of this process can be found on the Park Tool website.

Good luck!
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Old 03-13-09, 01:20 PM
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Is the shifter indexed or friction? If friction you need to increase the tension at the shifter. There should be an adjuster on the side of the shift lever. If indexed you probably need to add tension to the cable.

Al
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Old 03-13-09, 01:31 PM
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Sounds like you have a shifter or cable problem. Since it works fine when you hold the shifter, I am thinking shifter.
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Old 03-13-09, 02:58 PM
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Originally Posted by Al1943 View Post
Is the shifter indexed or friction? If friction you need to increase the tension at the shifter. There should be an adjuster on the side of the shift lever. If indexed you probably need to add tension to the cable.

Al
Never mind! I missed the part about these shifters being STI. They're indexed.

Al
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Old 03-13-09, 03:40 PM
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Originally Posted by LarDasse74 View Post
maybe the cable has slipped so much that you are using all the clicks in the shifter to get to the second-last cog and have no more clicks left to hold it on the last one
This is what I was thinking probably happened. I don't have time to get to it now but will report back when I do.

Thanks for the help so far, all.
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Old 03-14-09, 02:24 PM
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Originally Posted by j. hughes View Post
This is what I was thinking probably happened. I don't have time to get to it now but will report back when I do.

Thanks for the help so far, all.
Flip the small shift lever several times to make sure all of the cable is out of the shifter before attaching the cable to the derailleur with no slack.
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Old 03-15-09, 08:48 AM
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Originally Posted by LarDasse74 View Post
If a derailleur can be easily shifted into the last sprockt the limit screws generally do not need adjustment.

Good luck!
If the lever has to be held in order for the chain to remain on the large sprocket then I'd doubt if it can be shifted easily. I'd still bet on the L screw but one can only surmise.
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